Closed Circuit Flash Vapour Dryer is mainly used for processing materials containing organic solvents or materials that are toxic, harmful and easy to oxidise. The working principle is that the hot medium (such as nitrogen and other inert gases) is circulated in a closed loop system. The material is dried rapidly as the hot medium passes through it. Advantages include the effective avoidance of material oxidation and explosion risks, reduced organic solvent emissions, protection of the environment and operator safety. Moreover, the closed loop design reduces material loss, improves product recovery, has a high drying efficiency and can quickly evaporate water or other solvents from the material.

Working Principle

  In a closed loop system, firstly, hot inert gas (usually nitrogen) is warmed up to a specific temperature by a heater and then enters the drying chamber. Subsequently, the material to be dried is dosed into the drying chamber. The material is fluidised and rapidly dispersed in the drying chamber, driven by the high speed hot gas stream.

  Due to the temperature difference between the hot air stream and the material particles, the moisture (or other solvents) in the material will be rapidly vaporised into steam. The hot humid air with the vaporised steam leaves the drying chamber and enters a cyclone or bag filter, where the solid material is separated and collected, while the hot gas containing the steam enters a condenser.

  In the condenser, the steam is cooled and liquefied to achieve gas-liquid separation, while the inert gas is recovered, heated and re-circulated into the drying chamber, thus forming a closed-circuit cycle and continuously drying the material.

Equipment features:

- For materials containing organic solvents, toxic and hazardous, flammable and explosive materials, the use of inert gas (e.g. nitrogen) as the circulating medium can avoid contact between the materials and oxygen, reduce the risk of combustion, explosion, etc., to ensure the safety of the drying process.

- It can effectively prevent the organic solvent from volatilising into the atmosphere and reduce the pollution to the environment. Moreover, the closed-circuit circulatory system can recycle the solvent, which reduces the loss of solvent and meets the requirements of environmental protection.

- Fast drying speed, can complete the drying of materials in a short period of time, to minimise the impact on the quality of materials. And because it is a closed loop system, the material will not be contaminated by external impurities, which can ensure the purity and quality of the product.

- The hot gas is recycled in the closed circuit system, and can be used repeatedly after replenishing a certain amount of heat through the heater, which reduces the loss of heat, and compared with the traditional drying equipment, the utilisation rate of energy has been improved, and it has a better energy-saving effect.

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